(function() {
	function flexiable() {
		var rootFontSize = 100, //根节点字体大小
			designWidth = 750, //设计图的宽度
			doc = document.documentElement, //document元素
			clientWidth = doc.clientWidth; //当前屏幕的宽度
		var oMain = document.getElementById("app");
		if(clientWidth > designWidth) {
			// oMain.style.width = designWidth + "px";
			oMain.style.width = clientWidth + "px";
			oMain.style.margin = "0 auto";
			doc.style.fontSize = rootFontSize + "px";
		} else {
			oMain.style.width = clientWidth + "px";
			doc.style.fontSize = clientWidth / designWidth * rootFontSize + "px";
		}
	}
	flexiable();
	window.onresize = flexiable;
})();